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ALSA: intel8x0: Don't update period unless prepared 

commit c1f0616124 upstream.

The interrupt handler of intel8x0 calls snd_intel8x0_update() whenever
the hardware sets the corresponding status bit for each stream.  This
works fine for most cases as long as the hardware behaves properly.
But when the hardware gives a wrong bit set, this leads to a zero-
division Oops, and reportedly, this seems what happened on a VM.

For fixing the crash, this patch adds a internal flag indicating that
the stream is ready to be updated, and check it (as well as the flag
being in suspended) to ignore such spurious update.

Cc: <stable@vger.kernel.org>
Reported-and-tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Link: https://lore.kernel.org/r/s5h5yzi7uh0.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/356/head^2
Takashi Iwai 2021-05-16 18:17:55 +02:00 committed by Greg Kroah-Hartman
parent e227c60aa9
commit 1e94ffd074
1 changed files with 7 additions and 0 deletions
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7
sound/pci/intel8x0.c
View File

@ -354,6 +354,7 @@ struct ichdev {
unsigned int ali_slot; /* ALI DMA slot */
struct ac97_pcm *pcm;
int pcm_open_flag;
unsigned int prepared:1;
unsigned int suspended: 1;
};
@ -714,6 +715,9 @@ static inline void snd_intel8x0_update(struct intel8x0 *chip, struct ichdev *ich
int status, civ, i, step;
int ack = 0;
if (!ichdev->prepared || ichdev->suspended)
return;
spin_lock_irqsave(&chip->reg_lock, flags);
status = igetbyte(chip, port + ichdev->roff_sr);
civ = igetbyte(chip, port + ICH_REG_OFF_CIV);
@ -904,6 +908,7 @@ static int snd_intel8x0_hw_params(struct snd_pcm_substream *substream,
if (ichdev->pcm_open_flag) {
snd_ac97_pcm_close(ichdev->pcm);
ichdev->pcm_open_flag = 0;
ichdev->prepared = 0;
}
err = snd_ac97_pcm_open(ichdev->pcm, params_rate(hw_params),
params_channels(hw_params),
@ -925,6 +930,7 @@ static int snd_intel8x0_hw_free(struct snd_pcm_substream *substream)
if (ichdev->pcm_open_flag) {
snd_ac97_pcm_close(ichdev->pcm);
ichdev->pcm_open_flag = 0;
ichdev->prepared = 0;
}
return 0;
}
@ -999,6 +1005,7 @@ static int snd_intel8x0_pcm_prepare(struct snd_pcm_substream *substream)
ichdev->pos_shift = (runtime->sample_bits > 16) ? 2 : 1;
}
snd_intel8x0_setup_periods(chip, ichdev);
ichdev->prepared = 1;
return 0;
}